The unsprung weight of a vehicle, in particular a high performance motor car, is extremely significant in determining the handling and speed characteristics of the vehicle.
It is for this reason, among others, that cast alloy road wheels are fitted, as compared with pressed steel road wheels.
However, the final, detailed design of a cast alloy wheel is a compromise between, on the one hand, the optimum strength/weight ratio needed from a merely engineering/operational point of view and, on the other hand, the shape/volume of metal and mold construction required for the efficient casting of the metal during production.
The present invention is concerned with reducing the weight of a cast metal wheel, while at the same time keeping the manufacturing process and apparatus relatively simple.
International Patent Application WO81/03465 discloses a cast vehicle wheel which is of imperforate annular disc form and which has a bead seating wall spaced radially outward from a surface of the rim member in order to define a space between the rim and the bead seating wall.